1. Field
Embodiments of the invention relate to electronic systems, and more particularly, to protection systems for heterojunction integrated circuits (ICs).
2. Description of the Related Technology
Certain electronic systems are configured to protect circuits or components therein from transient electrical events. A transient signal event may be in the form of an electrical signal of a relatively short duration having rapidly changing voltage and high power. Transient signal events can include, for example, electrostatic discharge (ESD) events arising from the abrupt release of charge from an object or person to an electronic system.
Transient signal events can damage integrated circuits (ICs) inside an electronic system due to overvoltage conditions and/or high levels of power dissipation over relatively small areas of the ICs. Electronic circuit reliability is enhanced by providing protection devices to the pads of an IC. The protection devices can be incorporated on-chip or at a system-level, and can maintain the voltage level at the pads within a predefined safe range by transitioning from a high-impedance state to a low-impedance state when the voltage of the transient signal reaches a trigger voltage. Thereafter, the protection device can shunt at least a portion of the current associated with the transient signal before the voltage of a transient signal reaches a positive or negative failure voltage that can lead to one of the most common causes of IC damage. After activation, a protection device can remain in the low-impedance state as long as the transient signal voltage level is above a positive holding voltage or below a negative holding voltage.